Primary productivity in the Gulf of California, calculated from the relationship between superficial irradiance and chlorophyll in the euphotic zone

Abstract

The vertical distribution of chlorophyll a in the Gulf of California during the spring of 1992 showed a subsurface maxima between 10 and 50 m of depth. The average surface chlorophyll concentration was 0.71 mg m^–3. It was linearly related to the integrated chlorophyll of the euphotic zone (r² = 0.3 1, p < 0.001) and in the first optical depth (r² = 0.56, p < 0.00l), estimated from a spectral model. The highest values of the integrated chlorophyll of the euphotic zone were found at the region of the large islands (62.76 mg m^–2). The calculated values of integrated chlorophyll and incident irradiance were used to estimate primary productivity in the water column of the Gulf of California, throughout the parameter Ψ*. The predictions obtained with different values of this parameter were compared with measurements of primary productivity made in situ with the ¹⁴C method and estimated with natural fluorescente. Productivity increased to the north, reaching maximum values at the large islands region. Ψ*_p = 0.039 + 0.017 m² (gCla)^–1 is proposed for spring in the Gulf of California.